Once VOIs have been defined, they can be applied to the underlying data in various ways, to
•analyze the distribution of the pixel values enclosed in the VOIs;
•assess the geometry of the VOIs themselves like volume, surface area, sphericity;
•use the VOI geometry for modifying the data such as masking or cropping;
•create an atlas from the contour VOIs.
The calculations are started from two different locations, using the buttons above the VOIs list,
and using the tools in the panel in the lower right.